Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing my new design;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the sixth image thereof;

FIG. 7 is the seventh image thereof;

FIG. 8 is the eighth image thereof;

FIG. 9 is the ninth image thereof;

FIG. 10 is the tenth image thereof;

FIG. 11 is the eleventh image thereof;

FIG. 12 is the twelfth image thereof;

FIG. 13 is the thirteenth image thereof;

FIG. 14 is the fourteenth image thereof;

FIG. 15 is the fifteenth image thereof;

FIG. 16 is the sixteenth image thereof;

FIG. 17 is the seventeenth image thereof;

FIG. 18 is the eighteenth image thereof; and,

FIG. 19 is the nineteenth image thereof.

The broken lines around the figures show a display screen or portion thereof and the broken lines within the figures show unclaimed portions of the graphical user interface; the broken lines form no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-19. The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 